The proposed research seeks to understand the genetic specification of muscle development. The study will utilize mutants with abnormal muscle structure in the small nematode Caenorhabditis elegans to probe the process of sarcomere assembly. Through the application of genetic, ultrastructural and biochemical techniques, the structural gene for a myosin heavy chain gene has been identified. A detailed study of the mutants of this gene will be undertaken not only to learn more about the function of the myosin heavy chain in assembly, but also to identify regions of the genome regulating expression of this gene. Mutants in other gene affecting muscle will also be studied to learn how these gene products participate in muscle assembly. To facilitate these studies, additional components of the sarcomere will be identified chemically and immunologically, using mutants where possible to aid in this identification. Tests will be devised to recognize mutants affecting these products and where possible the gene product relationship will be established. Through the study of specific mutants one might learn more about the function of these components in muscle assembly. In addition, these mutants should be useful in identifying new mutants affecting muscle development. It is hoped that by gaining a detailed understanding of the genetic specification of muscle development in C. elegans, general principles will be found that underlie muscle development common to all higher organisms.